To provide a machine tool having a configuration for receiving load to be applied on a spindle unit 7 as uniformly as possible, to provide various machine tools having components used in common, and to construct a machining line incorporating various machine tools.

This vertical spindle unit 7 is guided to elevate and lower by upper and lower hydrostatic pressure guides 53, 54, a Y-axis moving mechanism 1 and an X-axis moving mechanism 3 have four Y linear bearings 12 and X linear bearings 32, respectively, and the spindle unit 7 is arranged among these four linear bearings 12 and 32. A spindle 91 for tool, a spindle 92 for chuck, and a clamp device 92 can be attached to the same spindle cylinder 71. The machining centers 15, 38, a lathe 16, a grinding machine 17, a robot machining machine 19 or the like having conveyors 97, respectively are arranged side by side to convey a workpiece 96a by transferring it onto each conveyor 97 one after another.